Linux only: One intrepid Ubuntu user has written up a nifty tutorial on using a webcam tool available in the standard repositories, motion, to turn a standard webcam into a motion-detecting security system. Once the camera sees something large enough move as to be suspicious, a custom script written by the blogger sends a notification to you through your Twitter account. It might not be the most reliable theft or home invasion prevention tool, but it could offer insight into when your roommates are invading your space or whether someone's using your laptop when they shouldn't be. The tutorial requires some command line work, but it's spelled out and explained pretty thoroughly. Photo by MShades.